crypto: tcrypt - Fix potential leak in test_aead_speed() if crypto_alloc_aead() fails

Fix a potential memory leak in the error handling of test_aead_speed(). In case
crypto_alloc_aead() fails, the function returns without going through the
centralized cleanup path. Reported by Coverity - CID 1163870.

Signed-off-by: Christian Engelmayer <cengelma@gmx.at>
Reviewed-by: Marek Vasut <marex@denx.de>
Acked-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>